19.1 Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
Chapter 19: Real-Time Systems
19.2 Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
Chapter 19: Real-Time Systems
■System Characteristics
■Features of Real-Time Systems
■Implementing Real-Time Operating Systems
■Real-Time CPU Scheduling
■An Example: VxWorks 5.x
19.3 Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
Objectives
■To explain the timing requirements of real-time systems
■To distinguish between hard and soft real-time systems
■To discuss the defining characteristics of real-time systems
■To describe scheduling algorithms for hard real-time systems
19.4 Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
Overview of Real-Time Systems
■A real-time system requires that results be produced within a
specified deadline period.
■An embedded system is a computing device that is part of a larger
system (i.e., automobile, airliner).
■A safety-critical system is a real-time system with catastrophic
results in case of failure.
■A hard real-time system guarantees that real-time tasks be completed
within their required deadlines.
■A soft real-time system provides priority of real-time tasks over non
real-time tasks.
19.5 Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
System Characteristics
■Single purpose
■Small size
■Inexpensively mass-produced
■Specific timing requirements